Self-forming-boom retracting and deploying apparatus



Oct. 28, 1969 F. c. RUSHING ET AL 3,474,976

SELFFQRMING-BOOM RETRACTING AND DEPLOYING APPARATUS Filed Jan. 26, 1968 WITNESSES INVENTORS Frank C. Rushing, BernurdJ.Murphy,Jr Ralph I.Houser a Bosfl S S ephcra 2 bxf w AG T United States Patent ABSTRACT OF DISCLOSURE .During boom retraction, a storage reel driven by a reversible motor via a unidirectional couplingpulls the uncurled boom in strip form tightly therearound under tension imposed by turning resistance of pinch rolls operatively connected to such motor via a slip clutch. During boom deployment, the motor-driven power rolls pull the strip from the storage reel against a friction drag opposing Claims 'ice closed in detail in US. Patents 3,144,104 and 3,177,987 to Weir et al. and Swaim, for example. i

In accord with features of theinvention, substantially the full length of the strip 2 is rolled up on the-storage reel 3, save for a leading section 5 between such reel and a boom guide 6 defining the boom entrance-exit portal its rotation, while the unidirectional coupling over-runs. F

In transit between storage reel and pinch rolls the strip is reversed in direction of travel. The motor couples to the slip clutch and unidirectional coupling via a drive system that tends to become locked when the motor is stopped.

The invention herein described was made in the course of a contract with the National Aeronautics and Space Administration.

BACKGROUND OF THE INVENTION Field of the invention Deploying and retracting apparatus for extendible booms formed from elongated thin strip material which is self-biased to curl transversely into a cylindrical configuration.

Description of the prior art Maintaining the strip in a tightly-wound controlled state during play-out, wind-in, and while stopped, is difficult to obtain in the prior art apparatus, particularly in the presence of vibration which can prevail in certain environments of the apparatus.

SUMMARY In the apparatus of the present invention, by virtue of the structural features of the present apparatus, a tension is maintained on the strip while it is being wound and unwound by motor operation from the storage reel and is locked in such tensioned state on the .reel during its storage.

BRIEF DESCRIPTION OF THE DRAWING The single figure is a three-dimensional schematic representation of a boom deploying and retracting apparatus embodying the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT have locking tabs and notches formed in its side edges, 7

such as shown, which mate together to provide an interlocked seam. Othfil booms with tabs and notches are disof the device; a stop 7 being attached to the end of the boom to prevent its complete retraction into the apparatus and onto the reel. During deployment of the booml the strip 2 is unwound from storage reel 3 by pinchrolls 9 and 10 arranged to accept the strip tangentially from such reel, pass it half way around the one reel in reverse of its direction leaving the storage reel and between the two reels for advancement outwardly through the guide'6; such strip having curled itself into a cylinder shape in transit from such pinch rolls to,such guide. A tension is maintained in the strip 2 on the storage reel 3v by a friction drag 12 which resists rotation of the storageireel 3 caused by the pinch-roll strip withdrawal. Rotary turning effort to accomplish such strip unwinding is obtained from a reversible motor 14 operatively connected to pinch roll 9 essentially by Way of a harmonic drive unit 15 in sealed cooperation with a sealed housing of the motor, a pair of gears 16 and 17, and a slip clutch 18, as well as the required number of shafts for rotary support and/or trans mission of such elements. A guide shoe 20 is disposed adjacent to the exit end of the pinch rolls 9 and 10 to prevent bending of the strip during playout which otherwise might result from increased thrust load on such strip as the boom 1 becomes extended to relatively long lengths. A frame means 2, shown fragmentally, provides support for the components of the apparatus, and the pinch roll 10 is biased toward pinch roll 9 to provide a squeeze force on the strip 2 by such as compression springs 24 acting on journal members 24 for the shaft of such roll 10.

During retraction of the boom 1, the strip 2 is caused to wind onto the storage reel 3 by the reversible motor 14 through the medium of a shaft 25, a unidirectional coupling 26, that overruns during boom depolyment, and a. gear 27 driven by gear 16. Such strip windup by the reel 3 is resisted by a rotary restraint imposed on the pinch rolls 9 and 10 by the slip clutch 18, the input end of which is also being driven by the motor 14 in the proper direction for the strip travel through the pinch rolls, but at a speed which is less than that required to keep up with such travel. Such restraint on the strip 2 being pulled around the storage reel by its rotation assures its becoming tightly wound thereon.

During deployment of the boom, the rotary components turn in the direction of the arrows marked thereon in the drawing, and such directions are reversed during boom retraction.

Once the motor 14 is stopped, during either boom retraction or deployment, the harmonic drive unit 15 tends to become self locking and unwinding of the strip 2 from the reel 3 is resisted by the friction drag 12 on such reel, and the slip clutch 18 which opposes pinch-roll rotation.

We claim:

1. Boom deploying and retracting apparatus COIIlpIlS- a thin elongated strip self-biased to curl edgewise into a cylindrical boom configuration when unrestrained,

a storage reel attached to one end of said strip and rotatable to cause such strip to be wound about its periphery and to permit unwinding of such strip therefrom,

a boom guide having an entrance-exit portal through which the opposite end of such strip extends in its cylindrical configuration as a boom,

rotatable pinch rolls between which said strip passes enroute from storage reel to boom guide,

3 4 r fi r q fewstfaining ea p g limited restraint l I, 3. The apparatus of claim 1, wherein a stop is attached rotation of said storage reel, to the end of the boom which prevents such end from a reversible motor, entering through said boom guide. 7 a unidirectional coupling in .rotary connection to the 4. The apparatus of claim 1, wherein said means for i axis of said storage reel, restraining rotation of said drive system when said motor a.v slip clutch in rotary connection to one pinch roll, and 5 is stopped is'embodied in the construction of the drive a drive system rotatably connecting said unidirectional system per se.

coupling and said slip clutch to said motor, 5. The apparatus of claim 1, wherein said motor comand means for restraining rotation of said drive system prises a' sealed housing in sealed cooperation with a sealed {when said motor is stopped, harmonic drive unit, a first gear driven by said unit, and a the aforesaid being so constructed and arranged that pair of gears driven by said first gear and in driving operation of the motor in one direction turns the storconnection to said unidirectional coupling and to said slip age reel via the unidirectional coupling to wind the clutch, respectively.

strip thereon against a rotary restraint imposed by References Cited 7 the pinch rolls and determined by the slip clutch be- UNITED STATES PATENTS ing driven by the motor in the strip wind-in direction but at a speed less than that required for the pinch 2,157,278 5/1939 Blafikmore 242 54 XR rolls to keep up with the rate at which the storage 3,144,104 8/1964 reel pulls the strip through such pinch rolls, and op- 3,144,215 8/1964 Klem 242-54 eration of the motor in the opposite direction causes 3,243,132 3/ 1966 Taylor et 24254 the slip clutch to turn the pinch rolls for withdrawing 3,361,377 1/1968 TrFxler 242-54 3,371,801 3/1968 wldegren 242-54 XR the strip tangentially from the storage reel against limited rotary restraint imposed on the storage reel 3,371,453 3/1968 by the friction restraining means While the unidirec- 'tional coupling is driven in an over-running state by MERVIN STEIN Pnmary Examiner Groskopfs et a1. 242-54 XR said motor. W. H. SCHROEDER, Assistant Examiner 2. The apparatus of claim 1, wherein the pinch rolls reverse the direction of strip travel between storage reel US. Cl. X.R.

and boom guide. 52-108; 212-55 

